Control circuit for power window regulator

ABSTRACT

Apparatus for opening and closing a window in accordance with a manually operated switch. A reversible electric motor having first and second field windings and an armature drivably connected to the window opens the window upon placement of the switch in a window-opening setting, which causes energization of the first winding. When the switch is placed in a window-closing setting the second winding is energized and the motor closes the window. Should the motor stall when closing the window due to the window encountering an obstacle the resulting decrease in the armature voltage below a certain level causes a voltage-sensing network and a current-directing network to deenergize the second winding and energize the first winding, thereby opening the window until the switch is removed from the window-closing setting or the window is fully opened. A time delay network is provided to prevent the voltage-sensing network from monitoring the armature voltage for a predetermined time after the switch is placed in the window-closing position so as to preclude voltage transients caused by starting the motor from effecting reversal of the motor during the predetermined time. A limit switch is positioned so as to be responsive to the window position and prevents the current-directing network from reversing the window travel when the window is substantially closed so as to allow the motor to stall when sealing the window closed.

United States Patent 72] Inventor Samuel B. Robbins Rochester, Mich.

211 Appl. No. 40,315

[22] Filed May 25, 1970 [45] Patented Nov. 30, 1971 73] Assignee GeneralMotors Corporation Detroit, Mich.

[54] CONTROL CIRCUIT FOR POWER WINDOW [56] References Cited UNITEDSTATES PATENTS 3,332,007 7/ i967 Livengood et al. 318/447 3,5 l 3,3745/1970 Koment 318/266 Primary ExaminerBenjamin Dobeck AssistantExaminer-K. L. Crosson Attorneys-J. L. Carpenter and Paul FitzpatrickABSTRACT: Apparatus for opening and closing a window in accordance witha manually operated switch. A reversible electric motor having first andsecond field windings and an armature drivably connected to the windowopens the window upon placement of the switch in a window-openingsetting, which causes energization of the first winding. When the switchis placed in a window-closing setting the second winding is energizedand the motor closes the window. Should the motor stall when closing thewindow due to the window encountering an obstacle the resulting decreasein the armature voltage below a certain level causes a voltage-sensingnetwork and a current-directing network to deenergize the second windingand energize the first winding, thereby opening the window until theswitch is removed from the window-closing setting or the window is fullyopened.

A time delay network is provided to prevent the voltagesensing networkfrom monitoring the armature voltage for a predetermined time after theswitch is placed in the windowclosing position so as to preclude voltagetransients caused by starting the motor from effecting reversal of themotor during the predetermined time.

A limit switch is positioned so as to be responsive to the windowposition and prevents the current-directing network from reversing thewindow travel when the window is substantially closed so as to allow themotor to stall when sealing the window closed.

PAIENTEDunv 30 197i R w. m

M Samuel 6. Robbins final ig h CONTROL CIRCUIT FOR POWER WINDOWREGULATOR This invention relates to power windows and, morespecifically, to control circuits for controlling the operation of powerwindows.

Power windows are in common usage types which differ widely, especiallyin their mechanical drive linkages. However, these devices are generallyrelated to their operation in that they usually are driven by reversibleelectric motors which are operated by a control circuit in accordancewith the setting of a manually operated switch. Though the controlcircuits employed in conjunction with these devices also are of manytypes their basic functions are few as all control circuits provide forthe opening and the closing of a window and, in some cases, also providefor automatic reversal of the window when it encounters a foreignobstruction while closing.

The subject invention provides all of the foregoing features bymonitoring the annature voltage of a window-operating motor having firstand second field windings selectively energizable for respectivelyopening and closing a window and by reversing the motor operationthrough redirecting current from the second winding to the first windingwhen the window is being closed and an obstruction has stalled the motorsufficiently for its armature voltage to fall below a certain level. Inaddition, the subject invention provides for preventing the motor frombeing reversed for a predetermined time after the second field windingis energized so as to prevent starting voltage transients of the motorfrom affecting the operation of the window. The subject inventionfurther provides for tightly sealing the window in its closed positionby allowing the motor to stall and its armature voltage to fall belowthe certain level without reversal of the motor by the control circuit.

These and other advantages of the subject invention will be apparentfrom the following description and accompanying drawing, which is aschematic diagram illustrating power window apparatus incorporating theprinciples of the subject invention.

Referring now to the drawing, may be part of a motor vehicle, isillustrated by way of example and without limitation as being operatedin accordance with the principles of the subject invention. The windowassembly includes a window frame 12, a window 14, and a gear and rackassembly 16 drivably connected to the window 14 for opening and closingthe window 14 in a well-known fashion. Since the window assembly 10 maytake several fonns, as is readily apparent to persons versed in the art,and is not itself a part of the present invention it needs no furtherdescription.

The window assembly 10 is drivably connected to a motor 18 throughsuitable apparatus (not shown) so as to enable the motor 18 to operatethe window 14. The motor 18 includes an armature 20 drivably connectedto the window assembly 10 today and are of many a window assembly 10which and first and second field windings 22 and 24 that are selectivelyenergized to rotate the armature 20 so as to operate the window 14. Inthe illustrated embodiment energization of the first winding 22 etTectsopening of the window 14 and energization of the second winding 24causes the armature 20 to close the window 14. Each of the windings 22and 24 are energized by a suitable power source, such as vehicle battery26, in accordance with the operation of a control circuit generallyindicated at 28.

As is seen in the drawing, the control circuit 28 is comprised of amanually operable switch 30 having window opening and window closingsettings which may be selected by a vehicle occupant for opening andclosing the window [4, a voltagesensing network 32 for sensing thearmature 20 voltage, a current directing network 34 that is responsiveto a signal from the voltage-sensing network 32 and the setting of theswitch 30 for controlling the energization of the first and secondwindings 22 and 24 so as to control the window 14 travel, a time delaynetwork 36 for preventing the voltage-sensing network 32 from monitoringthe armature 20 voltage for a predetermined time after the switch 30 isplaced in the window-closing setting so as to prevent voltage transientsgenerated by the starting of the motor 18 from affecting the motor 18operation and a limit switch 38 responsive to the window 14 position forpreventing reversal of the window 14 travel when the window 14 issubstantially closed so as to allow the motor 18 to stall when ittightly seals the window 14 closed.

Various types of switches may operate satisfactorily as the switch 30but in the illustrated embodiment the switch 30 is of the well-knowntype having a switch arm 40 which is normally spring biased to a center,or neutral, position as illustrated and which may be manually deflectedto a window-opening setting in which it engages a contact 42 or awindow-closing setting in which it engages a contact 44. When the switcharm 40 is placed in the window-opening setting it effects energizationof the first winding 22 by completing a circuit through the battery 26,the switch 22, leads 46, 48, and 50, the first winding 22, and thearmature 20. When the first winding 22 is energized the armature 20 isdriven so as to open the window 14.

To close the window 14 the switch arm 40 is placed in the window-closingsetting so as to energize the second winding 24. As the switch 30 isplaced in the window-closing setting a current path is completed fromthe battery 26 through a lead 52 to the time delay network 36, which iscomprised of a silicon control rectifier (SCR) 54 which controls a timedelay relay 56 that includes a time delay relay coil 58 and contact sets60 and 62 that are movable from their non'nal positions, illustrated insolid lines, to their operative positions, illustrated in dashed lines,when the relay coil 58 is energized. The time delay network 36 alsoincludes a timing branch 64 having a resistor 66 and a chargingcapacitor 68 which controls the triggering of the SCR 54. Since therelay coil 58 is initially deenergized placement of the switch 30 in thewindow-closing setting connects the battery 26 to the current-directingnetwork 34 both through the leads 46 and 48 and through the lead 52, thecontacts 60, and leads 70 and 72.

The current-directing network 34 includes a current-directing relay 74having a current-directing relay coil 76 and contacts 78 and 80 that aremovable from their illustrated solid line positions to their illustrateddashed line positions when the current-directing relay coil 76 isenergized. The current directing network also includes a holding relay82 having a holding relay coil 84 and a set of nonnally closed contacts86 that are opened when the holding relay coil 84 is energized, a pairof current-steering diodes 88 and 90, and a filter capacitor 92 inparallel with the current-directing relay coil 76 to render thecurrent-directing relay coil 76 insensitive to current transients. Whenthe switch 30 is placed in the windowclosing setting and the battery 26potential is applied to the current-directing network 34 through thelead 72 the currentdirecting relay coil 76 is energized, opening thenormally closed contacts 78 and closing the normally open contacts 80.When the contacts 78 are opened they prelude the energization of theholding relay coil 84, for reasons which will later become apparent,while closure of the contacts 80 energizes the second winding 24 bycompleting a current path from the battery 26 to the second winding 24through the switch 30, the lead 52, a lead 94, the contacts 80, and alead 96. Accordingly, upon placement of the switch 30 in thewindowclosing setting the window 14 is moved toward its closed position.

While the window 14 is being closed the capacitor 68 is being chargedthrough the resistor 66 until, at a predetermined time after the switch30 is placed in the window-closing setting, the charge on the capacitor68 turns on the SCR 54, energizing the time delay relay coil 58 so as tochange the positions of the contacts 60 and 62. Since the first winding72 is not energized at this time closure of the contacts 62 provides forthe sensing of the voltage across the armature 20 by thevoltage-directing network 32 through a current path which includes thefirst winding 22, the leads 50 and 48, a lead 98, the contacts 62, and alead 100.

The voltage-sensing network 32 controls the operation of thecurrent,directing relay coil 76 in accordance with the sensed armature20 voltage and includes a current-steering diode 102 for preventingcurrent feedback from the voltagesensing network 32 and a voltagedivider 104 which includes a pair of resistors 106 and 108 and apotentiometer 110 for adjusting the sensitivity of the voltage-sensingnetwork 32 to the armature 20 voltage. The voltage-sensing network 32also includes a pair of transistors 112 and 114 and appropriate biasingresistors 116 and 118 for detecting when the armature 20 voltage hasfallen below a certain level, and a filter capacitor 120 for preventingvoltage transients from being passed through the voltage divider 104 tothe transistors 112 and 114.

The operation of the control circuit 28 will now be explained in detail.When it is desired to open the window 14 the switch arm 40 of the switch30 is placed in the window-opening setting so as to engage the contact42 and cause the energization of the first field winding 22 through theleads 48 and 50. Since the battery 26 is directly connected to the firstfield winding 22 when the switch 30 is in the window-opening setting thewindow 14 will be opened until either it reaches its fully openedposition and the motor 18 is stalled or the setting of the switch 30 ischanged.

When it is desired to close the window 14 after it has been opened theswitch 30 is placed in the window-closing setting so as to engage thecontact 44 with the switch arm 40 and provide for the initialenergization of the second field winding 24 by energizing thecurrent-directing relay coil 76 through the contacts 60 and the leads 70and 72. Upon energization of the current-directing relay coil 76 thesecond winding 24 becomes energized through the lead 94, the contacts80, and the lead 96, thus causing the window 14 to begin to close.

At a predetermined time after the placement of the switch 30 in thewindow-closing setting, the time being sufficient for the motor 10 toreach steady-state operation and being determinable by proper selectionof the resistor 66 and the capacitor 68, the charge on the capacitor 68turns on the SCR 54. When the SCR 54 is turned on it conducts sufficientcurrent to energize the time delay relay coil 58. Since the SCR 54 isdirectly connected to the battery 26 through the switch 30 and the timedelay relay coil 58 is grounded the SCR 54 keeps the time delay relaycoil 58 energized so long as the switch 30 is held in the window-closingsetting.

Upon energization of the time delay relay coil 58 the cntacts 62 areclosed so as to enable the voltage-sensing network 32 to monitor thearmature 20 voltage as previously explained. In addition, energizationof the time delay relay coil 58 also changes the setting of the contacts60 so as to discon tinue energization of the current-directing relaycoil 76 through the leads 70 and 72 and to complete a current paththrough the normally closed limit switch 38 to the transistor 114. Sincethe motor has reached steady-state operation and the armature voltage isbeing sensed by the voltagesensing network 32 the voltage appliedthrough the voltage divider 104 to the base of the transistor 112 issufiiciently large to turn on the transistors 112 and 114. Accordingly,when the time delay relay coil 58 changes the setting of the contacts 60the current-directing relay coil 76 is energized through thetransistor-1114, the contacts 86, and the diode 88. While a discretetime is required for changing the position of the contacts 60, and hencethe energizing paths to the current-directing relay coil 76, thecapacitor 92 is selected to have sufficient charge storage capability tokeep the current-directing relay coil 76 energized until the transistor114 is turned on.

Should the window 14 encounter an obstacle while being closed the motor18 will be stalled, decreasing the voltage across the armature 20. Whenthe armature 20 voltage decreases below a certain level the voltageapplied to the base of the transistor 112 is insufficient to keep thetransistor 112 conductive, causing the transistors 112 and 114 to beturned off. When the transistor 114 is turned off the capacitor 92 isdischarged through the current-directing relay coil 76. Should thetransistor 1 14 remain nonconductive for longer than a certain timedetermined by the charge stored on the capacitor 92 thecurrent-directing relay coil 76 becomes deenergized and returns thecontacts 78 and 80 to their original positions illustrated in solidlines. The return of the contacts 80 to their solid line position opensthe current path through the lead 96 to the second field winding 24 soas to discontinue closure of the window 14 while the return of thecontacts 78 to their solid line position effects reversal of the motor18 so as to open the window 14 until the switch 30 is changed from thewindowclosing setting or the window 14 is fully opened. This is achievedby the contacts 78 connecting the emitter of the transistor 114, whichis at the potential of the battery 26, to the first winding 22 throughthe diode and the lead 50 so as to energize the first winding 22 andopen the window 14. In addition, closure of the contacts 78 connects theemitter of the transistor 114 to the holding relay coil 84, energizingthe holding relay coil 84 so as to open the contacts 86. The openedcontacts 66 thus preclude the current-directing relay coil 76 frombecoming energized, assuring that the first winding 22 will remainenergized so long as the switch 30 is held in the window-closing settingregardless of the voltage across the annature 20. The first fieldwinding 22 of the motor 18 thus remains energized through the contacts78 of the currentdirecting relay 74 so long as the switch arm 40 is heldin the window-closing setting. When the operator releases the switch arm40 it returns to the illustrated neutral position, discontinuing thesupply of power from the battery 26 to the control circuit 28 so as topermit subsequent operation as previously described.

While the encountering of an obstacle by the window 14 prior itsreaching its fully closed position causes automatic reversal of themotor 18 so as to open the window 14, the control circuit 28 providesfor tightly sealing the window 14 closed. This is achieved bypositioning the limit switch 38 so as to be responsive to the window 14position. Accordingly, when the window 14 is substantially in its closedposition it changes the setting of the limit switch 38 from,theillustrated solid line position to the position shown in dashed lines,which causes the energization of the current-directing relay coil 76through the lead 72 whenever the switch 30 is in the windowclosingsetting regardless of whether the time delay relay coil 58 is energized.The contacts 80 are thus held closed by the current-directing relay coil76 so as to provide continuous energization of the second field winding24 through the lead 96, which enables the motor 18 to stall whileclosing the window 14. Since the torque of the motor 18 is at a veryhigh level when the motor 18 is stalled a tight seal of the window 14 isas sured.

It is thus apparent that l have devised new and useful apparatus foroperating a power window under a variety of operating conditions, thoughpersons versed in the art will perceive that various modifications maybe made to this apparatus without departing from the spirit of myinvention.

lclaim:

1. Apparatus for moving a window between opened and closed positionscomprising, in combination, a power source, a reversible electric motordrivably connected to the window, the motor having an armature and beingoperable in first and second energized conditions effective to open andclose the window, and means for connecting the power source to the motoreffective to operate the window, the means including switch means havingat least window opening and window closing settings, the switch meansbeing operative in the window-opening setting to effect energization ofthe motor in the first energized condition by connecting the powersource in series circuit therewith so as to open the window, voltagesensing means for monitoring the armature voltage of the motor,current-directing means responsive to the switch position and thevoltage-sensing means both for completing a first circuit through thepower source and the motor when the switch means is in thewindow-closing setting and the monitored armature voltage is above acertain level effective to place the motor in the second energizedcondition and for opening the setting so as to prevent voltagetransients first circuit and completing a second circuit through thepower source and the motor when the switch means is in the windowclosingsetting and the monitored armature voltage has fallen below the certainlevel effective to place the motor in the first energized condition soas to reverse the motor and open the window, and means for preventingthe voltage-sensing means from monitoring the armature voltage for apredetermined time after the switch means is placed in thewindow-closing caused by starting the motor from efiecting reversal ofthe motor during the predetermined time.

2. Apparatus for moving a window between opened and closed positionscomprising, in combination, a power source, a reversible electric motorhaving an armature and being operable in first and second energizedconditions drivably coupled to the window effective to open and closethe window, and means for connecting the power source to the motoreffective to operate the window, the means including switch means havingat least window opening and window-closing settings, the switch meansbeing operative in the windowopening setting to place the motor in thefirst energized condition by connecting the power source in seriescircuit therewith so as to open the window, voltage-sensing means formonitor- -ing the armature voltage of the motor, current-directing meansresponsive to the switch position and the voltage sensing means forcompleting a first circuit through the power source and the motor whenthe switch means is in the windowclosing setting and the monitoredarmature voltage is above a certain level so as to place the motor inthe second energized condition and for opening the first circuit andcompleting a second circuit through the power source and the motor whenthe switch means is in the window-closing setting and the monitoredarmature voltage has fallen below the certain level so as to place themotor in the first energized condition, thereby effecting reversal ofthe motor and opening the window, means for preventing thevoltage-sensing means from monitoring the armature voltage for apredetermined time after placement of the switch means in thewindow-closing setting so as to prevent transient voltages caused bystarting the motor from efiecting reversal of the motor during thepredetermined time, and means responsive to the window position forpreventing the voltage-sensing means from affecting thecurrent-directing means when the window is substantially closed wherebythe motor is allowed to stall and the armature voltage is permitted tofall below the certain level so as to tightly seal the window closed.

3. Apparatus for opening and closing a window comprising, incombination, a reversible motor having first and second selectivelyenergizablefield windings and an annature drivably coupled to the windowfor opening and closing the window in accordance with the energizationof the first and second windings, a power source, a switch having atleast window opening and window closing settings, means for effectingenergization of the first winding by the power source when the switch isin the window-opening setting, means for energizing the second windingwith the power source when the switch is placed in the window-closingsetting, sensing means for monitoring the annature voltage, meansresponsive to the sensing means and the switch setting for effectingreversal of the motor by deenergizing the second winding and energizingthe first winding when the switch is in the window-closing setting andmonitored armature voltage has fallen below a certain level so as toopen the window until the switch is removed from the window-closingsetting or the window is fully opened, and means for precluding thesensing means from monitoring the armature voltage for a predeterminedtime after the switch is placed in the window-closing setting so as toprevent voltage transients generated upon stating the motor fromeffecting reversal of the motor during the predetennined time.

4. Apparatus for opening and closing a window comprising, incombination, a reversible motor having an armature drivably coupled tothe window for opening and closing the window and first and second fieldwindings selectively energizable effective to open and close the window,a power source, a switch having at least window opening and windowclosing settings, means for effecting energization of the first windingby the power source when the switch is in the window-opening setting,means for energizing the second winding with the power source when theswitch is placed in the window-closing setting, sensing means formonitoring the armature voltage, means responsive to the sensing meansand the switch setting for effecting reversal of the motor bydeenergizing the second winding and energizing the first winding whenthe switch is in the window-closing setting and the monitored armaturevoltage has fallen below a certain level so as to open the window untilthe switch is removed from the window-closing setting or the window isfully opened, means for precluding the sensing means from monitoring thearmature voltage for a predetermined time after the switch is placed inthe windowclosing setting so as to prevent voltage transients generatedupon starting the motor from effecting reversal of the motor during thepredetermined time, and means responsive to the window position forpreventing the voltage-sensing means from eflecting reversal of themotor when the window is substantially closed so as to permit thearmature voltage to fall below the certain level and the motor to stallwhen the motor seals the window closed.

5. Apparatus for opening and closing a window comprising, incombination, a power source, a reversible electric motor having firstand second selectively energizable field windings and an armaturedrivably connected to the window for opening and closing the window inaccordance with the energization of the first and second windings, amanually operable switch including at least window opening and windowclosing settings, the switch being effective in the window-openingsetting to connect the power source and the first winding in seriescircuit so as to energize the first winding and effect opening of thewindow, voltage-sensing means for monitoring the armature voltage of themotor, current-directing means responsive to the switch setting and thevoltage-sensing means for connecting the second winding in seriescircuit with the power source so as to energize the second winding solong as the switch is in the window-closing setting and the armaturevoltage remains above a certain level and for connecting the firstwinding in series circuit with the power source so as to energize thefirst winding so long as the switch is in the window-closing setting andafter the armature voltage has fallen below the certain level, placementof the switch in the window-closing setting thereby effecting closure ofthe window until the armature voltage falls below in the certain leveland opening of the window after the armature voltage has fallen belowthe certain level, time delay means for preventing the voltage-sensingmeans from affecting the operation of the current-directing means for apredetermined time after the switch is placed in the window-closingsetting so as to prevent the motor from opening the window during thepredetermined time, and window position responsive means for preventingthe voltage-sensing means from affecting the operation of thecurrent-directing means when the window is substantially closed wherebythe motor is allowed to stall and the armature voltage is allowed tofall below the certain level so as to enable the motor to tightly sealthe window closed, 1

6. Power window apparatus for opening and closing a window comprising,in combination, a power source, a reversible electric motor includingfirst and second selectively energizable field windings and an armaturedrivably connected to the window so as to open and close the window inaccordance with the energization of the windings, a selectively operableswitch having at least window opening and window closing settings forselectively energizing the first and second windings, the switch beingoperative in the window-opening setting to effect energization of thefirst winding by the power source so as to open the window, avoltage-sensing network for monitoring the armature voltage, thevoltage-sensing network including a switch responsive to the voltageacross the armature for detecting when the armature voltage is below acertain level, a current-directing network including a currentdirectingrelay responsive to the switch in the voltage-sensing network and thesetting of the selectively operable switch, the relay having a firstoperative condition when the selectively operable switch is in thewindow-closing setting and the monitored annature voltage is above thecertain level efiective to energize the second winding with the powersource so as to close the window and a second operative condition whenthe selectively operable switch is in the window-closing setting and themonitored armatured voltage has fallen below the certain level effectiveto cause energization of the first winding with the power source so asto open the window and means effective to maintain the relay in saidsecond operative condition so as to continue the opening of the windowuntil the selectively operable switch is removed from the window-closingsetting or the window is fully opened, a time delay network including arelay operative in a first condition to preclude the voltage-sensingnetwork from monitoring the voltage across the armature and theoperative in a second condition to permit the voltage-sensing network tomonitor the voltage across the armature and means for maintaining therelay in the first condition until the selectively operable switch hasbeen in the window-closingsetting for a predetermined time, therebypreventing voltage transients caused by starting the motor fromafi'ecting the operation of the current-directing network during thepredetermined time, and switch means responsive to the window positionfor keeping the current-directing relay in its first operative conditionwhen the window is substantially closed and the switch is in thewindow-closing setting, thereby preventing the voltage-sensing networkfrom placing the current-directing relay in its second operativecondition whereby the voltage across the armature is allowed to fallbelow the certain level while the motor stalls as it seals the windowclosed.

1. Apparatus for moving a window between opened and closed positionscomprising, in combination, a power source, a reversible electric motordrivably connected to the window, the motor having an armature and beingoperable in first and second energized conditions effective to open andclose the window, and means for connecting the power source to the motoreffective to operate the window, the means including switch means havingat least window opening and window closing settings, the switch meansbeing operative in the window-opening setting to effect energization ofthe motor in the first energized condition by connecting the powersource in series circuit therewith so as to open the window,voltage-sensing means for monitoring the armature voltage of the motor,current-directing means responsive to the switch position and thevoltage-sensing means both for completing a first circuit through thepower source and the motor when the switch means is in thewindow-closing setting and the monitored armature voltage is above acertain level effective to place the motor in the second energizedcondition and for opening the first circuit and completing a secondcircuit through the power source and the motor when the switch means isin the window-closing setting and the monitored armature voltage hasfallen below the certain level effective to place the motor in the firstenergized condition so as to reverse the motor and open the window, andmeans for preventing the voltage-sensing means from monitoring thearmature voltage for a predetermined time after the switch means isplaced in the window-closing setting so as to prevent voltage transientscaused by starting the motor from effecting reversal of the motor duringthe predetermined time.
 2. Apparatus for moving a window between openedand closed positions comprising, in combination, a power source, areversible electric motor having an armature and being operable in firstand second energized conditions drivably coupled to the window effectiveto open and close the window, and means for connecting the power sourceto the motor effective to operate the window, the means including switchmeans having at least window opening and window-closing settings, theswitch means being operative in the window-opening setting to place themotor in the first energized condition by connecting the power source inseries circuit therewith so as to open the window, voltage-sensing meansfor monitoring the armature voltage of the motor, current-directingmeans responsive to the switch position and the voltage sensing meansfor completing a first circuit through the power source and the motorwhen the switch means is in the window-closing setting and the monitoredarmature voltage is above a certain level so as to place the motor inthe second energized condition and for opening the first circuit andcompleting a second circuit through the power source and the motor whenthe switch means is in the window-closing setting and the monitoredarmature voltage has fallen below the certain level so as to place themotor in the first energized condition, thereby effecting reversal ofthe motor and opening the window, means for preventing thevoltage-sensing means from monitoring the armature voltage for apredetermined time after placement of the switch means in thewindow-closing setting so as to prevent transient voltages caused bystarting the motor from effecting reversal of the motor during thepredetermined time, and means responsive to the window position forpreventing the voltage-sensing means from affecting thecurrent-directing means when the window is substantially closed wherebythe motor is allowed to stall and the armature voltage is permitted tofall below the certain level so as to tightly seal the window closed. 3.Apparatus for opening and closing a window comprising, in combination, areversible motor having first and second selectively energizable fieldwindings and an armature drivably coupled to the window for opening andclosing the window in accordance with the energization of the first andsecond windings, a power source, a switch having at least window openingand window closing settings, means for effecting energization of thefirst winding by the power source when the switch is in thewindow-opening setting, means for energizing the second winding with thepower source when the switch is placed in the window-closing setting,sensing means for monitoring the armature voltage, means responsive tothe sensing means and the switch setting for effecting reversal of themotor by deenergizing the second winding and energizing the firstwinding when the switch is in the window-closing setting and monitoredarmature voltage has fallen below a certain level so as to open thewindow until the switch is removed from the window-closing setting orthe window is fully opened, and means for precluding the sensing meansfrom monitoring the armature voltage for a predetermined time after theswitch is placed in the window-closing setting so as to prevent voltagetransients generated upon starting the motor from effecting reversal ofthe motor during the predetermined time.
 4. Apparatus for opening andclosing a window comprising, in combination, a reversible motor havingan armature drivably coupled to the window for opening and closing thewindow and first and second field windings selectively energizableeffective to open and close the window, a power source, a switch havingat least window opening and window closing settings, means for effectingenergization of the first winding by the power source when the switch isin the window-opening setting, means for energizing the second windingwith the power source when the switch is placed in the window-closingsetting, sensing means for monitoring the armature voltage, meansresponsive to the sensing means and the switch setting for effectingreversal of the motor by deenergizing the second winding and energizingthe first winding when the switch is in the window-closing setting andthe monitored armature voltage has fallen below a certain level so as toopen the window until the switch is removed from the window-closingsetting or the window is fully opened, means for precluding the sensingmeans from monitoring the armature voltage for a predetermined timeafter the switch is placed in the window-closing setting so as toprevent voltage transients generated upon starting the motor fromeffecting reversal of the motor during the predetermined time, and meansresponsive to the window position for preventing the voltage-sensingmeans from effecting reversal of the motor when the window issubstantially closed so as to permit the armature voltage to fall belowthe certain level and the motor to stall when the motor seals the windowclosed.
 5. Apparatus for opening and closing a window comprising, incombination, a power source, a reversible electric motor having firstand second selectively energizable field windings and an armaturedrivably connected to the window for opening and closing the window inaccordance with the energization of the first and second windings, amanually operable switch including at least window opening and windowclosing settings, the switch being effective in the window-openingsetting to connect the power source and the first winding in seriescircuit so as to energize the first winding and effect opening of thewindow, voltage-sensing means for monitoring the armature voltage of themotor, current-directing means responsive to the switch setting and thevoltage-sensing means for connecting the second winding in seriescircuit with the power source so as to energize the second winding solong as the switch is in the window-closing setting and the armaturevoltage remains above a certain level and for connecting the firstwinding in series circuit with the power source so as to energize thefirst winding so long as the switch is in the window-closing setting andafter the armature voltage has fallen below the certain level, placementof the switch in the window-closing setting thereby effecting closure ofthe window until the armature voltage falls below in the certain leveland opening of the window after the armature voltage has fallen belowthe certain level, time delay means for preventing the voltage-sensingmeans from affecting the operation of the current-directing means for apredetermined time after the switch is placed in the window-closingsetting so as to prevent the motor from opening the window during thepredetermined time, and window position responsive means for preventingthe voltage-sensing means from affecting the operation of thecurrent-directing means when the window is substantially closed wherebythe motor is allowed to stall and the armature voltage is allowed tofall below the certain level so as to enable the motor to tightly sealthe window closed.
 6. Power window apparatus for opening and closing awindow comprising, in combination, a power source, a reversible electricmotor including first and second selectively energizable field windingsand an armature drivably connected to the window so as to open and closethe window in accordance with the energization of the windings, aselectively operable switch having at least window opening and windowclosing settings for selectively energizing the first and secondwindings, the switch being operative in the window-opening setting toeffect energization of the first winding by the power source so as toopen the window, a voltage-sensing network for monitoring the armaturevoltage, the voltage-sensing network including a switch responsive tothe voltage across the armature for detecting when the armature voltageis below a certain level, a current-directing network including acurrent-directing relay responsive to the switch in the voltage-sensingnetwork and the setting of the selectively operable switch, the relayhaving a first operative condition when the selectively operable switchis in the window-closing setting and the monitored armature voltage isabove the certain level effective to energize the second winding withthe power source so as to close the window and a second operativecOndition when the selectively operable switch is in the window-closingsetting and the monitored armatured voltage has fallen below the certainlevel effective to cause energization of the first winding with thepower source so as to open the window and means effective to maintainthe relay in said second operative condition so as to continue theopening of the window until the selectively operable switch is removedfrom the window-closing setting or the window is fully opened, a timedelay network including a relay operative in a first condition topreclude the voltage-sensing network from monitoring the voltage acrossthe armature and the operative in a second condition to permit thevoltage-sensing network to monitor the voltage across the armature andmeans for maintaining the relay in the first condition until theselectively operable switch has been in the window-closing setting for apredetermined time, thereby preventing voltage transients caused bystarting the motor from affecting the operation of the current-directingnetwork during the predetermined time, and switch means responsive tothe window position for keeping the current-directing relay in its firstoperative condition when the window is substantially closed and theswitch is in the window-closing setting, thereby preventing thevoltage-sensing network from placing the current-directing relay in itssecond operative condition whereby the voltage across the armature isallowed to fall below the certain level while the motor stalls as itseals the window closed.